"They'll (the divers) return back to their base and we'll continue our search of the beaches for any further evidence," he said.

"We've been searching along Tallow Beach to Broken Head and from Wategos through to Brunswick Heads."

Sgt Neaves said the divers conducted a "very methodical" search of the coastline, grottos and caves, taking into account the rip that was operating at the time.

"They've done a comprehensive search of the area where he was last sighted and there was no evidence found," he said.

Mr Butler was last seen struggling against a strong rip at the rocky base of Cape Byron last Saturday morning.

He had been surfing off Tallow Beach with two friends, American Levi Fahrenholtz and Englishman Mike Fuller, before the three were caught in a rip and swept towards the cliffs. Mr Butler's friends managed to escape from the rip but he hasn't been seen since.

Police have urged surfers and swimmers to take care.

"If you're inexperienced or new to the area, consider the conditions carefully and take advice from experts, surf schools and locals," Sgt Neaves said. "And if in doubt, don't go into the surf."